Add the ability to follow the agent as it makes edits (#29839)

Nathan here: I also tacked on a bunch of UI refinement.

Release Notes:

- Introduced the ability to follow the agent around as it reads and
edits files.

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Co-authored-by: Nathan Sobo <nathan@zed.dev>
Co-authored-by: Max Brunsfeld <maxbrunsfeld@gmail.com>

crates/workspace/Cargo.toml

@@ -36,7 +36,6 @@ clock.workspace = true
 collections.workspace = true
 component.workspace = true
 db.workspace = true
-derive_more.workspace = true
 fs.workspace = true
 futures.workspace = true
 gpui.workspace = true